Microscope system

ABSTRACT

A Microscope system comprises, at least, an objective lens which changes luminous flux from an object into parallel luminous flux, an afocal variable magnification optical system which changes a diameter of luminous flux emanated from the objective lens into a different diameter of luminous flux, and an image forming optical system by which an image forming of the parallel luminous flux emanated from the afocal variable magnification optical system is carried out, and the following conditions are satisfied: 
 
2· NA ( ob )· FL ( ob )≧30 
 
6≦ Lexz/X ≦10 
where NA(ob) is the maximum effective aperture size of an objective lens, FL (ob) is the focal length of the objective lens, X=2·NA(ob)·FL(ob), and Lexz is the distance from an object surface to the most distant end of the afocal variable magnification optical system.

This application claims benefits of Japanese Application No. 2004-270010filed in Japan on Sep. 16, 2004, the content of which is incorporated bythis reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to a microscope system that isexcellent in operation performance with bright image and magnificationcan be varied.

2. Description of the Related Art

Single objective lens type stereomicroscope is known as a conventionalexample of a microscope with excellent workability and extendibility.FIG. 1 is a view showing an outline composition of an optical system ofsuch single objective lens type stereomicroscope. The objective lens ofthis kind of microscope has a focal length that is in the range of about200 to 40 mm, and is constituted such that comparatively low observationmagnification and a long free working distance can be secured.

However, in the conventional single objective lens typestereomicroscope, due to restrictions of the distance between two rightand left optical paths from an afocal variable magnification opticalsystem to an image forming lens, etc., an incident diameter of theafocal variable magnification optical system is limited to ½ or lessthan the effective diameter of the objective lens. Especially, indesigning in which a magnification ratio by the afocal variablemagnification optical system is enlarged, the diameter of a lens of theafocal variable magnification optical system is limited at the sidewhere magnification becomes high, and accordingly it tends to becomeinsufficient in brightness of the image.

This is the same in such case that imaging is carried out by leadingluminous flux which has transmitted either of the right or the leftafocal variable magnification optical system to an image sensor. When afluorescence image is observed by combining a lighting system and filterfor observing a fluorescence image, by using an objective lens having aconsiderably big effective diameter compared with then afocal variablemagnification optical system, sufficient brightness cannot not beobtained although a large observation view is secured. Especially in anoptical system having a large observation range in this way, it is easyto generate a careless omission of a weak and minute fluorescence markeretc.

Then, in specific magnification and a specific focal length, in order toincrease the brightness of an image, it is necessary to enlarge theaperture size NA of a lens. To enlarge the aperture size NA of a lens isthe same as the diameter of luminous flux emanated from an objectivelens becoming large Here, a diameter of luminous flux emanated from anobjective lens is expressed as follows:2·NA(ob)·FL(ob)  (1)where NA (ob) is an aperture size of an objective lens, and FL (ob) is afocal length of the objective lens.

Generally a diameter of exit luminous flux of the objective lensobtained from the condition (1) is a value from about several mm to 20mm in a microscope, and it is generally in tendency which becomes smallas the focal length of the objective lens becomes short. Also in astereomicroscope of a single objective-lens type, although the diameterof exit luminous flux of the objective lens itself is about 40 mm ormore, the effective diameter of the exit luminous flux becomes as avalue of around 20 mm, since it is limited by the effective diameter ofan afocal variable magnification optical system.

SUMMARY OF THE INVENTION

A microscope system according to the present invention comprises, atleast, an objective lens which changes luminous flux from an object intoparallel luminous flux,

an afocal variable magnification optical system which changes a diameterof luminous flux emanated from the objective lens into a differentdiameter of luminous flux, and an image forming optical system by whichan image forming of the parallel luminous flux emanated from the afocalvariable magnification optical system is carried out, and the followingconditions are satisfied:2·NA(ob)·FL(ob)≧306≦Lexz/X≦10where NA (ob) is the maximum effective numerical aperture of anobjective lens, FL (ob) is a focal length of an objective lens, X=2, NA(ob), and FL (ob), Lexz is a distance from an object surface to the mostdistant end of an afocal variable-magnification-optical-system.

The microscope system according to the present comprises at least, anobjective lens which changes luminous flux from an object into parallelluminous flux, an afocal variable magnification optical system whichchanges a diameter of luminous flux emanated from the objective lensinto a different diameter of luminous flux, and an image forming opticalsystem by which an image forming of the parallel luminous flux emanatedfrom the afocal variable magnification optical system is carried out,wherein the objective lens, the afocal variable magnification opticalsystem and the image forming optical system can be arranged keeping aninterval more than L=F(TL)/2 and the following condition is satisfied:D(TL)≧EXP(max)*1.25where L is a distance from an exit end of a zoom lens to an entrance endof the image forming lens, F (TL) is a focal length of the image forminglens, D (TL) is an effective diameter of the image forming lens. And EXP(max) is a diameter of the greatest exit pupil of the afocal variablemagnification optical system.

The microscope system of the present invention comprises at least, twoand more objective lenses which change luminous flux from an object intoparallel luminous flux, an afocal variable magnification optical systemwhich changes a diameter of luminous flux emanated from the objectivelens into a different diameter of luminous flux, and an image formingoptical system by which an image forming of the parallel luminous fluxemanated from the afocal variable magnification optical system iscarried out, and two or more objective lenses mentioned above satisfiesthe following conditions;2·NA(ob)·FL(ob)≧30X(Max)/X(Min)<1.25M(obH)/M(obL)≧2L(ob Max)/L(ob Min)<1.1where NA (ob) is the maximum effective aperture size of each objectivelens, FL (ob) is a focal length of each objective lens, X (Max) is themaximum of 2·NA (ob)·FL (ob), X (Min) is the minimum value of 2·NA(ob)·FL (ob), M (obH) is the magnification of an objective lens with thehighest magnification, M (obL) is the magnification of an objective lenswith the lowest magnification, L (ob Max) is the maximum of a distancefrom an object surface to the utmost surface of the objective lens, andL (ob Min) is the minimum value of the distance from an object surfaceto the utmost surface of the objective lens.

The microscope system of the present invention comprises at least, anobjective lens which changes luminous flux from an object into parallelluminous flux, a first afocal variable magnification optical systemwhich changes a diameter of luminous flux emanated from the objectivelens into a different diameter of luminous flux, and an image formingoptical system by which image forming of the parallel luminous fluxemanated from the first afocal variable magnification optical system iscarried out, and a second afocal variable magnification opticalsystem(ca) which can be inserted between the objective lens and thefirst afocal variable magnification optical system, and the followingconditions are satisfied:M(ca)≦0.8ENP(max)≧EXP(ob)[M(ca)where M (ca) is magnification of the second afocal variablemagnification optical system, EXP (max) is a diameter of the greatestexit pupil of the first afocal variable magnification optical system,EXP (ob) is a diameter of the exit pupil of the objective lens.

Furthermore, the microscope system of the present invention ischaracterised in that in the microscope system mentioned above, ailluminating light having a selected wavelength is projected on asample, and observation of the light (fluorescence etc.) havingdifferent wavelength from the illuminating light emitted from the sampleis possible, and a filter for separating wavelength of illuminatinglight and wavelength of the light for observation is arranged withinlimits satisfying the following condition:L(f)=F(TL)/3.where L (f) is a distance from the exit end of the afocal variablemagnification optical system to a filter, F (TL) is a focal length ofthe image forming lens.

According to the microscope of the present invention, effective NA canbe obtained by taking advantage of a diameter of the objective lens tothe maximum extent.

According to the microscope of the present invention, as the focallength of an objective lens is within range of about 200 mm to 40 mm, afree working distance having about 180 mm to 20 mm can be obtained. Andsince the free working distance is 50 mm or more, access to a sample canbe easily performed while observing a sample under a microscope.

According to the microscope of the present invention, an observer canperform access to a sample easily, observing a sample under themicroscope.

Moreover, according to the present invention, since in a free workingdistance about 20 mm, at the time of observing a sample in a container,such as a culture dish, when the sample is exchanged, the worksmentioned above can be done without retracting an objective lens eachtime.

Thus, the microscope according to the present invention demonstrates anexcellent operation performance as a microscope for work.

Furthermore, according to the microscope of the present invention sincea distance from the object surface to the last surface of the afocalvariable-magnification-optical-system is limited while taking a largeeffective aperture size of the objective lens, a suitable optical pathlength for observation in an easy posture is obtained.

Moreover, from a stand point of operation for selecting, and dissectingan observation sample, it is desirable that an optimal magnificationsuitable for each of uses can be selected easily and quickly in order tocarry out observation and photographing of a specific part under onemicroscope, and furthermore, since it is desirable to selectcontinuously a magnification, the microscope of the present inventionhas a zoom type magnification lens by which a wide range ofmagnification can be chosen arbitrarily by single operation. Further, itis possible to make a constitution for obtaining two or moremagnifications by inserting two or more afocal variable magnificationoptical systems selectively, even though it may be inferior inconvenience to some extent.

According to the microscope of the present invention, it is possible toobserve a view in a wider range, to obtain a much higher resolution, andto select an objective lens suitable for each of uses according to anindividual use. Therefore, according to the microscope of the presentinvention, it is possible to apply for much various uses. In that case,as for objective lenses, a distance from an object surface to an exitend of an objective lens are nearly same mutually, and a focal positiondoes not shift greatly with exchange of the objective lens. Therefore,operation performance can be remarkably improved.

According to the microscope of the present invention since it has big NA(aperture size), while securing a long free working distance and a largeobservation view, a bright fluorescence image can be obtained,especially when selecting work of an ecology sample is carried out byusing as a marker protein (GFP etc.) which emits fluorescence, and whenobserving a sample for which marking of an internal organs of smallanimals, such as a rat, etc has been carried out. Thus, a carelessomission of a marker can be prevented. Furthermore, since a sufficientbright fluorescence image is obtained, an increase in efficiency of workcan be attained, without making surroundings of a sample and a wholeroom dark when fluorescence observation is carried out.

These and other features and advantages of the present invention willbecome apparent from the following detailed description of the preferredembodiments when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an outline composition of an optical systemof conventional single objective lens type stereomicroscope.

FIG. 2 is a diagram showing the optical composition of the microscopesystem of the first embodiment according to the present invention.

FIGS. 3A, 3B, and 3C are sectional views along the optical axis showingan example of an afocal zoom lens used for the microscope system of thepresent invention, and showing minimum magnification state, a middlemagnification state, and a maximum magnification state, respectively.

FIG. 4 is a sectional view along the optical axis of an image forminglens combinable with an afocal zoom lens.

FIG. 5 is sectional view along the optical axis of the optical system inwhich the afocal zoom lens shown in FIG. 3, and the image forming lensshown in FIG. 4 which is arranged keeping a suitable interval arecombined.

FIGS. 6A, 5B, 6C, and 6D are sectional views along the optical axis ofmutually different objective lenses combined with the microscope systemaccording to the present invention, respectively.

FIG. 7 is a sectional view along the optical axis of the optical systemconcerning the present invention which combines an objective lens and asecond afocal magnification lens.

FIGS. 8A to 8D, 8E to 8H, and 81 to 8L are the aberration diagramsshowing spherical aberration, in which the afocal zoom lens shown inFIG. 4, and the image forming lens shown in FIG. 5 which is arrangedkeeping a suitable interval are combined, when the afocal zoom lensshown in FIG. 4, and the image forming lens shown in the FIG. 5 arearranged with a suitable interval, and a composite focus distance of theafocal zoom lens and the image forming lens is 56 mm, 177 mm, and 560mm, respectively.

FIGS. 9A to 9D, 9E to 9H, and 9I to 9L are aberration diagrams showingspherical aberration, coma aberration, astigmatism, and magnificationchromatic aberration respectively, when the objective lens shown in FIG.6C, the afocal zoom lens shown in FIG. 3, and the image forming lensshown in the FIG. 4 are arranged with a suitable interval, and acomposite focus distance of the afocal zoom lens and the image forminglens is 56 mm, 177 mm, and 560 mm, respectively.

FIGS. 10A to 10D, 10E to 10H, and 10I to 10L are aberration diagramsshowing spherical aberration, coma aberration, astigmatism, andmagnification chromatic aberration respectively, when the objective lensshown in FIG. 6C, the afocal zoom lens shown in FIG. 3, and an imageforming lens shown in the FIG. 4 are arranged with a suitable interval,and a composite focus distance of the afocal zoom lens and the imageforming lens is 56 mm, 177 mm, and 560 mm, respectively.

FIGS. 11A to 1D, 11E to 11H, and 11I to 11L are aberration diagramsshowing spherical aberration, coma aberration, astigmatism, andmagnification chromatic aberration respectively, when the objective lensshown in FIG. 6C, the afocal zoom lens shown in FIG. 3, and the imageforming lens shown in the FIG. 4 are arranged with a suitable interval,and a composite focus distance of the afocal zoom lens and the imageforming lens is 56 mm, 177 mm, and 560 mm, respectively.

FIGS. 12A to 12D, 12E to 12H, and 12I to 12L are aberration diagramsshowing spherical aberration, coma aberration, astigmatism, andmagnification chromatic aberration respectively, when the objective lensshown in FIG. 6C, the afocal zoom lens shown in FIG. 3, and the imageforming lens shown in the FIG. 4 are arranged with a suitable interval,and a composite focus distance of the afocal zoom lens and the imageforming lens is 56 mm, 177 mm, and 560 mm, respectively.

FIG. 13 is an aberration diagram showing spherical aberration, comaaberration, astigmatism, and magnification chromatic aberrationrespectively, when the objective lens shown in FIG. 7, the afocal zoomlens shown in FIG. 3, and the image forming lens shown in the FIG. 4 arearranged with a suitable interval, and a composite focus distance of theafocal zoom lens and the image forming lens is 56 mm, 177 mm, and 560mm, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Prior to explanation of embodiments of the present invention, functionand action of the present invention will be explained.

In a microscope of the present invention, in order to increase thebrightness of an observation image, it is designed so that the followingcondition may be satisfied:2·NA(ob)·FL(ob)>30  (2)where, NA (ob) is the maximum effective aperture size of an objectivelens, and FL (ob) is the focal length of the objective lens.

The condition (2) means that an image becomes brighter more than twice,when in the same magnification value it is compared with an objectivelens having magnification which is about 20. It is because imagebrightness has a relation proportional to square of the diameter of exitluminous flux.

In order to obtain a brighter image, a value of the condition (2) shouldbe a bigger value than 30. In order to get much bigger value than 30 inthe condition (2), it is necessary to enlarge a diameter of the lensitself fairly. However, due to problems such as productivity and cost,the diameter of the lens is suitable for up to around 50.

In another viewpoint, in case that a suitable magnification range (forexample, about 10 times) is kept, a full length of an afocal variablemagnification optical system has a tendency for the full length tobecome long as the diameter of luminous flux entered from the objectivelens becomes large, from reasons for aberration correction etc.

Also in order to be able to maintain a suitable observation posture overthe full length, without bending of a special optical path etc, sizethat is about 50 are suitable for a diameter of exit luminous flux ofthe objective lens.

Furthermore, the distance from an object surface to the most distant endof an afocal variable magnification optical system becomes to a rangethat is 180 mm to 500 mm by satisfying the following condition:6≦Lexz/X≦10  (3)where X is 2 NA (ob)·FL (ob), NA (ob) is the maximum effective aperturesize of the objective lens, FL (ob) is a focal length of the objectivelens, and Lexz is a distance from an object surface to the most distantend of the afocal variable magnification optical system.

By arranging a suitable image forming lens, and a body tube and the likehaving the image forming lens on an afocal variable magnificationoptical system satisfying conditions (2) and (3), it becomes possible tooffer a microscope with a suitable observation posture.

Furthermore, in an image forming optical system comprising an objectivelens, an afocal variable magnification optical system which changes adiameter of luminous flux emanated from the objective lens into adifferent diameter of luminous flux, and an image forming optical systemby which an image forming of the parallel luminous flux emanated fromthe afocal variable magnification optical system is carried out,expansion of the system is possible.

Concretely, by inserting a half mirror or a filter for introducinglighting luminous flux for a fluorescence observation into parallelluminous flux, or by inserting a half mirror and the like for branchingall or a part of the luminous flux toward a side direction, this systemcan be applied to various observation methods and applications.

In order to give such expansion possibility, it is desirable that anoptical component can be arranged so as to have an interval more than avalue obtained by the following condition:L=F(TL)/2  (4)where L is a distance from an exit end of a zoom lens to an entrance endof the image forming lens, F (TL) is a focal length of the image forminglens.

Furthermore, for securing a sufficient amount of light at acircumference part of an observation view, and for preventing fromgeneration of conspicuous view unevenness etc. it is desirable tosatisfy the following condition.D(TL)≧EXP(max)*1.25  (5)where D (TL) is an effective diameter of an image forming lens

In a fluorescence observation, a half mirror for projecting illuminatinglight with a selected wavelength to a sample, and observing on adifferent wavelength from the illuminating light, and a filterseparating wavelength are inserted into an interval having a valueobtained by the condition (3) mentioned above. A mirror unit to whichthese filters and half mirrors are set is arranged, and two or moremirror units are set so that the fluorescence image of two or morewavelengths can be chosen easily.

In order to constitute two or more of these mirror units with necessaryminimum size and to achieve to make them at low cost, it is desirable tosatisfy the following condition:L(f)=F(TL)/3  (6)where L (f) is a distance from an exit end of a zoom lens to a filter,and F (TL) is a focal length of the image forming lens.

In a microscope system comprising, an objective lens, an afocal variablemagnification optical system which changes a diameter of luminous fluxemanated from the objective lens into a different diameter of luminousflux, and an image forming optical system by which an image forming ofthe parallel luminous flux emanated from the afocal variablemagnification optical system is carried out, it is possible to choose adifferent objective lens and the like, when carrying out an observationin much wider range of magnification than such range that is variable bythe afocal variable magnification optical system in the magnificationrange, and when a longer free working distance and a larger aperturesize are needed.

The objective lens used for the microscope of the present invention canhave outstanding operation performance and system extendibility withoutshifting a focus position greatly, when they are exchanged, also in anobjective lens corresponding to various uses by satisfying the followingconditions:2·NA(ob)·FL(ob)≧30  (2)X/(Max)X(Min)<1.25—(7)M(obH)/M(obL)≧2  (8)L(ob Max)/L(ob Min)<1.1  (9)where NA (ob) is the maximum effective numerical aperture of eachobjective lens, FL (ob) is a focal length of each objective lens, X(Max) is the maximum of 2·NA (ob)·FL (ob), X (Min) is the minimum valueof 2·NA (ob)·FL (ob), M (obH) is the magnification of an objective lenswith the highest magnification, M (obL) is the magnification of anobjective lens with the lowest magnification, L (ob Max) is the maximumof a distance from an object surface to the utmost surface of theobjective lens, and L (ob Min) is the minimum value of the distance froman object surface to the utmost surface of the objective lens.

In the condition (8), when magnification range of M(obH)/M(obL)≧2x isgiven, it becomes possible to choose an objective lens of suitablemagnification or an aperture size according to various uses. Forexample, that is an objective lens having long free working distance, oran objective lens having large aperture size and high resolution power,etc.

In order to utilize sufficiently each objective lens and effectivediameter of an afocal variable magnification optical system,respectively without futility, it is desirable for a diameter of exitluminous flux of each of objective lenses to have nearly same size. Ifthe condition (7) is not satisfied, a state where each of effectivediameters is not fully utilized efficiently in either of an objectivelens or an afocal variable magnification optical system will occur.

By the way, in an objective lens having a big aperture size NA at theobject side and high resolution power, generally, each of a free workingdistance, a focal length, and a full length is small as well, and thediameter of an exit pupil is from several mm to about 20 mm.

If such objective lens having a small exit pupils and a variablemagnification optical system having a large diameter of an incidencepupil are combined, there is a problem that the large diameter of a lensof the variable magnification optical system becomes not onlyineffectual, but also it is easy to become superfluous magnification toNA at the object side, and accordingly only a little faded image isobtained.

So, in order to obtain a suitable observation magnification according tothe aperture size at the object side, it is necessary to arrange asecond variable magnification optical system that the diameter of apupil becomes appropriate between an objective lens and a variablemagnification optical system,

Such second variable magnification optical system is an afocal variablemagnification optical system when an objective lens is designed forinfinite distance; it is desirable to satisfy the following conditions:M(ca)≦0.8  (10)ENP(max)≧EXP(ob)/M(ca)  (11)where M (ca) is a magnification of the second afocal variablemagnification optical system, ENP (max) is a diameter of the maximumexit pupil of the first afocal variable magnification optical system,and EXP (ob) is a diameter of the exit pupil of the objective lens.

In order to make a difference between the diameter of the exit pupil ofthe objective lens and the diameter of the incidence pupil of the firstvariable magnification optical system small by expanding the diameter ofthe exit pupil of the objective lens, magnification of the secondvariable magnification optical system M (ca) must have a value smallerthan 1.

This is because a pupil diameter and magnification have a relation of aninverse proportion in an afocal variable magnification optical system.

As a condition to acquire an effect of fully expanding an exit pupil ofan objective lens, M (ca) is 0.8 or less. When it is more than 0.8,sufficient effect cannot be obtained.

As for conditions to obtain an effect for expanding fully the exit pupilof an objective lens, it is desirable that the condition of M (ca)mentioned above is satisfied, and the following condition is satisfied:ENP(max)≧EXP(ob)/M(ca)

This is because a problem such that the effective aperture size NA at anobject side becomes small is generated when exceeding this condition.

Hereafter, embodiments of the present invention will be explained usingdrawings.

First Embodiment

FIG. 2 is a diagram explaining an optical composition of the microscopesystem of the first embodiment according to the present invention.

As shown in FIG. 2, a microscope system 1 of the first embodiment isequipped with an objective lens 2 and an afocal variable magnificationoptical system 3, and a sample can be observed through an eyepiece 4.

As shown in FIG. 2, the microscope system of the first embodiment isconstituted such that it has a long free working distance WD, a distanceto the exit end of a zoom lens is suppressed moderately. In FIG. 2, Lexzis a distance from an object surface to the most distant end of theafocal variable magnification optical system. In FIG. 2, light pathfigure is a diagram showing a state when the magnification of the afocalvariable magnification optical system is the minimum.

In the first embodiment, the value of the condition (2) is 45, and thevalue of the condition (3) is 7.5. However, when values of the condition(2) and (3) are smaller than this, for example, when the value of thecondition (2) is 30 and the value of the condition (3) is 6, since theeye point position at the time of observing through a microscope becomeslow, it is necessary to combine a holding body so as to keep the eyepoint at a high position.

When the values of the conditions (2) and (3) are larger than the valuesof the conditions in the first embodiment, for example, when such valuesare 50 and 10, conversely, it is necessary to combine the holding bodyso as to keep the eye point position lower.

Thus, it becomes possible to offer a microscope such that a suitableobservation posture can be maintained by using the values of theconditions (2) and (3).

Second Embodiment

FIG. 3 is a sectional view along the optical axis showing an example ofan afocal zoom lens used for the microscope system of the presentinvention.

FIG. 3A shows a minimum magnification state of the afocal zoom lens.

FIG. 3B shows a middle magnification state.

FIG. 3C shows a maximum magnification state.

As shown in FIG. 3, the afocal zoom lens 5 has two or more lens groupsG1, G2, G3, G4, G5, and G6, wherein magnification can be changed bychanging a distance from an object surface to each of these lens groupsG1 to G6.

FIG. 3 shows that the diameter of an exit pupil becomes the maximum whenthe magnification is the minimum, and the diameter of then exit pupilbecomes the minimum when the magnification is the maximum.

The second embodiment shows a case that ENP (max)=45 and the full lengthis 190. when reducing of the full length is made until it becomes ENP(max)=30, and the full length is set to 127. The afocal zoom lens 5 canbe combined with, for example, an image forming lens.

FIG. 4 is a sectional view along the optical axis of an image forminglens combinable with the afocal zoom lens 5. The image forming lens 6shown in FIG. 4 has two or more lens groups G7 and G8. A light pathfigure shown in FIG. 4, shows a range of luminous flux transmitted toview when the diameter of an exit pupil of an afocal zoom lens becomesthe maximum, wherein an effective diameter of an image forming lens ismore than EXP(max)*1.25.

A desired focal length can be obtained by combining with the afocal zoomlens 5 shown in FIG. 3.

The focal length of the image forming lens shown in FIG. 4 is 180, andthe effective diameter of the image forming lens is φ36.

FIG. 5 is sectional view along the optical axis of the optical system inwhich the afocal zoom lens 5 shown in FIG. 3, and the image forming lens6 shown in FIG. 4 which is arranged keeping a suitable interval arecombined.

As shown in FIG. 5, since it has become more than EXP(max)*1.25 to thediameter of the maximum exit pupil of the afocal zoom lens, even when Lthat is a distance from an exit end of a zoom lens to an entrance end ofthe image forming lens is large, sufficient luminous flux is securedover circumferential portion of an image.

The distance L from the exit end of the zoom lens to the entrance end ofan image forming lens, and focal length F (TL) of the image forming lensin the second embodiment are shown below:L=100 (=F(TL)/1.8)F(TL)=180

Third Embodiment

In FIGS. 6A to 6D, an example of an objective lens combined with themicroscope system according to the present invention is shown. A lightfigure shown in FIG. 6 shows a state where magnification of an afocalvariable magnification optical system is the minimum, and an observationrange becomes the maximum. An objective lens 7 a shown in FIG. 6A has alens group G9 having negative power, a focal length of which is longerthan the full length of a lens, and a lens group G10 having positivepower. Objective lenses 7 b to 7 d each of focal lengths which isshorter than the full length of the lens have lens groups G11, G14 andG17 having positive power, lens groups G12, G15 and G18 having weakpower, and lens groups G13 G16, and G19 that consist of a meniscus lensa convex surface of which is directed to an object side and a positivesingle lens, respectively.

As shown in FIGS. 6A to 6D, in any of objective lenses, the full lengthis set to be nearly same such as around 140 mm, and set to have a lensdiameter which becomes nearly same to a diameter of an exit pupil.Concretely, a focal length of each objective lens is 180 to 56, and M(obH)/M (obL)=3.2. Any of objective lenses are designed as follows:2·NA(ob)·FL(ob)=40˜45(around 40 to 45)L(ob Max)/L(ob Min)=1.04.

Fourth Embodiment

FIG. 7 is a sectional view along the optical axis of the optical systemwhich combines an objective lens and a second afocal magnification lens.An objective lens 8 shown in FIG. 7 has a large aperture size NA at anobject side, and constituted such that a focal length and full lengthare short.

This objective lens 8 is constituted so as to be combined with thesecond afocal magnification lens 9.

As shown in FIG. 7, the diameter of an exit pupil of the objective lensis enlarged by the second afocal variable magnification optical system.In the fourth embodiment, as of the second afocal variable magnificationoptical system it is magnification M (ca)=0.5, and the diameter of theexit pupil of the objective lens is enlarged to twice as much size asthis.

Moreover, each of the full length of the objective lens shown in FIGS.6A to 6D can be nearly same by keeping a suitable interval between thisobjective lens to the second afocal variable magnification opticalsystem.

The objective lens shown in this embodiment, although the aperture sizeNA at the object side is large, the diameter of the lens iscomparatively small.

Therefore, a problem occurs as follows: namely, when the magnificationof the first variable magnification optical system is low, the luminousflux transmitted to a circumference portion of view cannot betransmitted, and accordingly only the center portion of the view can beobserved. However, when the magnification of the first variablemagnification optical system is high, such problem does not occur.

With respect to the afocal zoom lens shown in FIG. 3, the followingnumerical data will be shown below. These are a radius of curvature of asurface of each optical component shown in order from an object imageside, a wall thickness of each optical component, or an interval betweensurfaces of each optical component shown in order from the object imageside (unit: mm), an index of refraction at d line of each opticalcomponent shown in order from the object side, and Abbe's number of eachoptical component shown in order from the object side. Numerical data 1Surface Radius of Surface (or air) Refraction Abbe's number curvatureinterval index number 1 143.584 6.5 1.43875 94.93 2 −151.471 4.5 1.6730038.15 3 −406.964 0.5 4 86.266 7 1.43875 94.93 5 −182.860 4 1.67300 38.156 −627.529 D1 7 289.274 5.6 1.73800 32.26 8 −40.355 3 1.77250 49.60 942.167 3.2 10 −172.814 2.8 1.77250 49.60 11 22.430 4.5 1.73800 32.26 12267.473 D2 13 −38.998 2.8 1.67790 55.34 14 −112.304 D3 15 −104.447 4.51.43875 94.93 16 −37.846 D4 17 86.418 4.5 1.43875 94.93 18 −96.570 D5 19−62.848 3.5 1.67790 55.34 20 −174.072 0

A value of each intervals D1 to D5 in FIGS. 3A to 3C and numerical dataof the composite focus distance FL with the image forming lens shown inFIG. 4 are shown as follows: D1 6.000 49.684 65.362 D2 63.114 19.4303.752 D3 33.132 30.751 4.429 D4 27.652 25.599 8.000 D5 3.200 7.63451.555 FL 56.0 177.0 560.0

Numerical data of the image forming lens shown in FIG. 4 are shown asfollows. Numerical data 2 Surface Radius of Surface (or air) RefractionAbbe's number curvature interval index number 1 69.845 9.98 1.4970081.54 2 −54.633 4.65 1.80610 40.92 3 −172.571 9.58 4 60.898 11.431.83400 37.16 5 −82.872 5.76 1.65412 39.68 6 31.904 126.94

Numerical data of the image forming lens shown in FIG. 6A are shown asfollows. Numerical data 3 Focal length FL 180 mm Full length 142.67 mmworking distance WD 71.9 mm Surface Radius of Surface (or air)Refraction Abbe's number curvature interval index number (objectsurface) 71.927 1 INF 5.73 1.63980 34.46 2 −84.402 0.66 3 67.942 4.21.48749 70.23 4 31.409 29.33 5 −23.188 5.65 1.80440 39.59 6 −182.83911.43 1.49700 81.54 7 −37.796 1 8 −75.171 4.9 1.49700 81.54 9 −41.1640.8 10 −206.366 7 1.48749 70.23 11 −46.433

Numerical data of the objective lens shown in FIG. 6B are shown asfollows. Focal length FL 90 mm Full length 143.86 mm Working distance71.6 mm Surface Radius of Surface (or air) Refraction Abbe's numbercurvature interval index number (object surface) 71.6 1 INF 7 1.5163364.14 2 −104.9906 1 3 153.8759 8.5 1.61800 63.33 4 INF 4 5 −93.1665 5.521.61340 44.27 6 75.2978 11 1.43875 94.99 7 −77.5003 1.756 8 53.2217 15.11.60562 43.70 9 91.3981 5.08 1.61340 44.27 10 47.5573 5.3 11 198.4043 81.43875 94.93 12 −105.7296

Numerical data of the objective shown in FIG. 6 C are shown as follows:Focal length FL 75 mm Full length 137.98 mm Working distance WD 56 mmSurface Radius of Surface (or air) Refraction Abbe's number curvatureinterval index number (object surface) 56.01 1 INF 9.67 1.48749 70.23 2−55.209 2 3 216.606 8.06 1.43875 94.99 4 −108.481 4.28 5 −48.133 7.441.67300 38.15 6 377.434 17.3 1.49700 81.54 7 −54.117 0.3 8 46.887 13.831.60562 43.70 9 −171.744 5.4 1.61340 44.27 10 39.276 6.69 11 210.938 71.43875 94.99 12 −185.942

Numerical data of the objective shown in FIG. 6 D are shown as follows:Focal length FL 56 mm Full length 140.02 mm Working distance WD 34.9 mmSurface Radius of Surface (or air) Refraction Abbe's number curvatureinterval index number (object surface) 34.911 1 INF 11.75 1.51633 64.152 −42.021 0.2 3 INF 5.88 1.71850 33.52 4 76.173 11.45 1.49700 81.61 5−76.173 1.294 6 INF 14.27 1.49700 81.61 7 −38.336 12.35 1.64450 40.82 8−220.439 7.913 9 57.314 19.91 1.65016 39.39 10 −57.314 8.36 1.6445040.82 11 47.362 5.462 12 INF 6.27 1.51633 64.15 13 −78.2

Numerical data of the objective lens and the afocal lens shown in FIG. 7are shown as follows. Focal length FL 36 mm Full length 141.339 mm M(ca)0.5 EXP(ob) 14.4→28.8 Surface Radius of Surface (or air) RefractionAbbe's number curvature interval index number (object INF 3.788 surface)1 −6.636 1.63 1.74100 52.65 2 19.677 5.81 1.43875 94.97 3 −7.977 0.214 421.662 3.96 1.43875 94.97 5 −21.662 0.300 6 19.677 3.07 1.43875 94.97 7−32.827 0.571 8 12.378 6.25 1.43875 94.97 9 −12.378 3.53 1.52682 51.1310 7.977 5 11 −6.046 1.79 1.69680 56.47 12 53.090 4.03 1.43875 94.97 13−9.458 0.39 14 146.241 3.6 1.56907 71.30 15 −16.025 51 16 −40.635 2.181.69680 56.47 17 21.438 5.7 1.78472 25.68 18 51.704 22.146 19 210.8023.19 1.68893 31.08 20 51.047 6.84 1.45600 90.31 21 −200.548 0.29 22201.409 6.06 1.48749 70.21 23 −43.1969

FIGS. 8A to 8D, 8E to 8H, and 8I to 8L are aberration diagrams showingspherical aberration, coma aberration, astigmatism, and magnificationchromatic aberration, when the afocal zoom lens shown in FIG. 4, and theimage forming lens shown in FIG. 5 are arranged keeping a suitableinterval, and a composite focus distance of the afocal zoom lens and theimage forming lens is 56 mm, 177 mm, and 560 mm, respectively.

FIGS. 9A to 9D, 9E to 9H, and 9I to 9L are aberration diagrams showingspherical aberration, coma aberration, astigmatism, and magnificationchromatic aberration, when the objective lens shown in FIG. 6A, theafocal zoom lens shown in FIG. 3, and the image forming lens shown inFIG. 4 are arranged keeping a suitable interval, and a composite focusdistance of the afocal zoom lens and the image forming lens is 56 mm,177 mm, and 560 mm, respectively.

FIGS. 10A to 10D, 10E to 10H, and 10I to 10L are aberration diagramsshowing spherical aberration, coma aberration, astigmatism, andmagnification chromatic aberration when the objective lens shown in FIG.6B, the afocal zoom lens shown in FIG. 3, and the image forming lensshown in FIG. 4 are arranged with a suitable interval, and a compositefocus distance of the afocal zoom lens and the image forming lens is 56mm, 177 mm, and 560 mm, respectively.

FIGS. 11A to 11D, 11E to 11H, and 11I to 11L are aberration diagramsshowing spherical aberration, coma aberration, astigmatism, andmagnification chromatic aberration when the objective lens shown in FIG.6C, the afocal zoom lens shown in FIG. 3, and the image forming lensshown in FIG. 4 are arranged with a suitable interval, and a compositefocus distance of the afocal zoom lens and the image forming lens is 56mm, 177 mm, and 560 mm, respectively.

FIGS. 12A to 12D, 12E to 12H, and 12I to 12L are aberration diagramsshowing spherical aberration, coma aberration, astigmatism, andmagnification chromatic aberration, respectively, when the objectivelens shown in FIG. 6D, the afocal zoom lens shown in FIG. 3, and animage forming lens shown in the FIG. 4 are arranged with a suitableinterval, and a composite focus distance of the afocal zoom lens and theimage forming lens is 56 mm, 177 mm, and 560 mm, respectively.

FIG. 13 is an aberration diagram showing spherical aberration, comaaberration, astigmatism, and magnification chromatic aberrationrespectively, when the objective lens shown and the afocal zoom lensshown in FIG. 7, the afocal zoom lens shown in FIG. 3 and an imageforming lens shown in the FIG. 4 are arranged with a suitable interval,and a composite focus distance of the afocal zoom lens and the imageforming lens is 560 mm. When a composite focus distance of the afocalzoom lens and the image forming lens is shorter, an effective diameterin the objective lens becomes insufficient, and accordingly, luminousflux directed toward the circumference portion of view cannot be passed.

1. A microscope system comprising at least, an objective lens whichchanges luminous flux from an object into parallel luminous flux, anafocal variable magnification optical system which changes a diameter ofluminous flux emanated from the objective lens into a different diameterof luminous flux, and an image forming optical system by which imageforming of the parallel luminous flux emanated from the afocal variablemagnification optical system is carried out, wherein the followingconditions are satisfied:2·NA(ob)·FL(ob)≧306≦Lexz/X≦10 where NA (ob) is the maximum effective numerical aperture ofan objective lens, FL (ob) is a focal length of an objective lens, X=2,NA (ob)·FL (ob), Lexz is a distance from an object surface to the mostdistant end of the afocal variable magnification optical system.
 2. Amicroscope system comprising at least, an objective lens which changesluminous flux from an object into parallel luminous flux, an afocalvariable magnification optical system which changes a diameter ofluminous flux emanated from the objective lens into a different diameterof luminous flux, and an image forming optical system by which imageforming of the parallel luminous flux emanated from the afocal variablemagnification optical system is carried out, wherein the afocal variablemagnification optical system and the image forming optical system can bearranged keeping an interval more than L=F (TL)/2, wherein the followingcondition is satisfied:D(TL)≧EXP(max)*1.25 where L is a distance from an exit end of the afocalvariable magnification optical system to the entrance end of an imageforming lens, F (TL) is a focal length of the image forming lens, and D(TL) is an effective diameter of the image forming lens, EXP (max) is adiameter of the greatest exit pupil of the afocal variable magnificationoptical system.
 3. A microscope system comprising at least, an objectivelens which changes luminous flux from an object into parallel luminousflux, an afocal variable magnification optical system which changes adiameter of luminous flux emanated from the objective lens into adifferent diameter of luminous flux, and an image forming optical systemby which image forming of the parallel luminous flux emanated from theafocal variable magnification optical system is carried out, whereinsaid two or more objective lenses satisfies the following conditions:2·NA(ob)·FL(ob)≧30X(Max)/X(Min)<1.25M(obH)/M(obL)≧2L(ob Max)/L(ob Min)<1.1 where NA (ob) is the maximum effective numericalaperture of each objective lens, FL (ob) is a focal length of eachobjective lens, X (Max) is the maximum of 2·NA (ob)·FL (ob), X (Min) isthe minimum value of 2·NA (ob)·FL (ob), M (obH) is the magnification ofan objective lens with the highest magnification, M (obL) is themagnification of an objective lens with the lowest magnification, L (obMax) is the maximum of a distance from an object surface to the utmostsurface of the objective lens, and L (ob Min) is the minimum value ofthe distance from an object surface to the utmost surface of theobjective lens.
 4. A microscope system comprising at least, an objectivelens which changes luminous flux from an object into parallel luminousflux, a first afocal variable magnification optical system which changesa diameter of luminous flux emanated from the objective lens into adifferent diameter of luminous flux, an image forming optical system bywhich image forming of the parallel luminous flux emanated from thefirst afocal variable magnification optical system is carried out, and asecond afocal variable magnification optical system which can beinserted between the objective lens and the first afocal variablemagnification optical system, wherein the following conditions aresatisfied:M(ca)≦0.8ENP(max)≧EXP(ob)/M(ca) where M (ca) is the magnification of the secondafocal variable magnification optical system, EXP (max) is a diameter ofthe greatest exit pupil of the first afocal variable magnificationoptical system, and EXP (ob) is a diameter of the exit pupil of theobjective lens.
 5. The microscope system according to any of claims 1 to4, wherein the illuminating light having a selected wavelength isprojected on a sample, observation of the light (fluorescence etc.)having different wavelength from the illuminating light emitted from thesample is possible, and a filter for separating wavelength ofilluminating light and wavelength of the light for observation isarranged within limit satisfying the following condition:L(f)=F(TL)/3. where L (f) is a distance from the exit end of the afocalvariable magnification optical system to a filter, and F (TL) is a focallength of the image forming lens.